PRODUCT GUIDE
Liquid PAC vs Solid PAC: Which Form Fits Your Plant
Liquid and solid polyaluminium chloride carry the same active chemistry; the aluminium hydrolysis that cleans your water is identical. What differs is everything around the chemical: how much water you ship, how long it keeps, what winter does to it and how much labour dosing takes. The right form is a logistics answer, not a chemistry answer.
The two forms at a glance
| Property | Liquid PAC (~10% Al2O3) | Solid PAC (28% / 29%) |
|---|---|---|
| Dosing volume | roughly 3x the solid dose | baseline |
| Freight efficiency | low - most of the tonne is water | high - active material only |
| Preparation | none - pump straight or dilute 1:5 | dissolve 5 - 10% solution on site |
| Shelf life | months, temperature-dependent | 12 months or more, dry storage |
| Cold weather | freezing damages performance | unaffected |
| Typical fit | nearby plant, mild climate, automated dosing | export, long storage, seasonal plants |
Converting between the two
Because liquid runs near 10% Al2O3 against 28% for industrial solid, the same aluminium dose takes roughly three times the liquid volume. If your current solid dose is 20 mg/L, expect around 60 mg/L of liquid product, adjusted by jar test. When suppliers quote both forms, compare on delivered cost per kilogram of Al2O3, never per tonne of product - liquid wins that misleading comparison automatically.
Mixing labour is the quiet advantage of liquid: no dissolving station, no undissolved lumps in strainers, no operator dependency on make-up procedure. For plants that lose dosing accuracy whenever the shift changes, ready-to-pump liquid removes a whole failure mode.
Where each form wins
Liquid fits plants close to the factory: the freight penalty shrinks with distance, a mild climate removes the freezing risk, and continuous high consumption keeps tote turnover quick. Drinking-water plants should confirm the liquid product is produced and documented to the drinking-water standard before switching.
Solid fits everything that ships far: export buyers get high freight efficiency and a year of shelf life, cold-winter plants avoid the thawed-product question entirely, and stores rooms hold months of buffer without a tank farm. Smaller plants also find solid easier to control - bags are countable inventory in a way that tank levels are not.
Frequently asked questions
Does liquid PAC work as well as solid?
Yes - once diluted to the same aluminium dose, performance is the same, provided the liquid has been stored within its temperature range and used within shelf life. Performance problems with liquid almost always trace back to frozen or overheated storage.
How do I size a liquid storage tank?
Work backwards from daily consumption in litres (dose in mg/L times flow, divided by about 10% Al2O3 content and adjusted for density near 1.2), then hold two to four weeks of stock. Keep a second tank or tote reserve so one delivery delay cannot stop the plant.
Can I switch from solid to liquid mid-season?
Yes, with a jar test bridge: run both products side by side on your raw water, convert the dose with the factor-of-three rule of thumb, then change over while watching effluent turbidity daily for the first week. Keep the solid line as backup until the new routine is stable.